YOU NEED YOUR TEXT BOOKS TODAY. GO GET ‘em IF YOU DON’T HAVE THEM JQ: Almost everyone knows that most of the Earth’s surface is covered in water. Where did all that water come from? Link

Bathymetry The study of the depth/topography of the floor of a body of water. 2

SONAR Short for Sound Navigation and Ranging Originally used for submarine detection during WWII Used since to map ocean floor topography 3

4 BATHYMETRY OF THE OCEAN FLOOR Structures on the ocean floor are mapped by SONAR - sound navigation and ranging (echo sounding) (speed of sound in H20) depth = time x 1500 meters/sec 2 (round trip) sea floor

Do Now: Sound travels at 1500 meters per second in water. How deep is the ocean bottom if the sonar signal is received 6 seconds after it was sent? 6 seconds there and back 2 trips 1500 meters 1 second = 4500 meters deep

Do Now: Sound travels at 1500 meters per second in water. The Mariana trench is 10,809 meters deep. How long will it take for sound to travel from the surface of the water above and back? Show your work. 10,809 m one way2 R.T 1500 meters 1 second = 14.4 sec

7 THE WORLD OCEAN Covers 71 % of the planet (59.4 % is seafloor) Divided into major basins – Atlantic (N & S),Pacific,Arctic, Indian, Southern *Pacific – largest & deepest

8 NOAA Continental Margin: the submerged outer edge of a continent marks the transition between continent and ocean, composed of shelf, slope & rise a. continental shelf - underwater extension of the continent, most biologically productive area because of light availability b. continental slope – sloping transition between the continent (granite) and the deep-ocean floor (basalt) - sediments tumbling down the slope can form turbidity currents which cut submarine canyons (deep, V-shaped valley running perpendicular to the shoreline) c. continental rise – wedge of sediments covering the joint between ocean crust and continental crust Continental Margin

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Do Now: Sit next to a partner. Have your partner close his or her eyes. Once they are closed, ask them to make a click noise or say a sentence. Have them continue to keep their eyes closed. Then, hold the textbook flat about 5 inches from their face. Ask them to make the same sounds. Ask them if they can tell if something is near their face. TEST SUBJECT KEEP EYES CLOSED THE WHOLE TIME. Experiment, by moving the book farther away, or to the right or left, and ask them if they can describe the position/distance.

11 Ocean Basin Features: a. abyssal plain - flat, featureless region similar to a desert; common in Atlantic and Indian Oceans, rare in the Pacific b. abyssal hill - occur where sediment is not thick enough to cover the underlying rock completely. Usually extinct volcanoes or small formations of rock once extruded in molten form. c. seamount - peaks of volcanic mountains (sea mountains, completely underwater) d. guyot - submerged, inactive volcano flattened by erosion; like e. island - seamounts extending out of the water. They differ from continents because they have no margins. f. trenches – arc-shaped depression in the deep-ocean floor with very steep sides and flat sediment-filled bottoms, associated with subduction zones where ocean crust is being recycled into the mantle

12 Mt. Everest, at 29,000 ft., could fit into the Mariana trench and still be 7,000 ft. below sea level. g. MOR - 40,000 mile long mountain range where new oceanic floor is being formed. Divergent plate boundaries are found in all parts of the ocean - not just in the middle of the Atlantic. Iceland is a large section of the MOR extending above the water. NOAA

13 JQ: Do any organisms use sonar? Explain Also called Bio Sonar, many dolphins, toothed-whales, cave swiftlets, shrews, tenrecs Link